Electric regulator



May 8, 1945. F. NEWTON ELECTRIC REGULATOR Filed March 24, 1942' "kwik Iv Patented May 8, 1945 ELECTRIC REGULATOR Frederick Newton, Derby, England,l assigner to Newton yBrothers (Derby) Limited, Derby, England A Application March 24, 1942, Serial No. 436,049

13 Claims. (Cl. 201-51) This invention relates to electric regulators and more particularly has reference to a carbon pile regulator suitable for use under extraordinary conditions.

Carbon pile regulators have been found very desirable for use inv controlling the electrical systems of airplanes and other means of transportation. Regulators of the carbon pile type operate effectively under all normal `and even most abnormal conditions of airplane flight. However, under `extreme flight conditions such as exist during power dives considerable vibration occurs and if the direction of vibration is parallel to the axis of the carbon pile, it may be possible that there will be a tendency for the vibration to effect separation of adjacent discswithin the pile when the compressive force applied to the pile is low. The separation of the discs due to such conditions is very detrimetal because of the sparking which takes place thereon.

An object ofr this invention is to avoid the disadvantages in carbon pile regulators as pointed out above. r

Another object of this invention is to provide a carbon pile regulator having means for avoiding the separation of adjacent discs of the carbon pile due to vibratory `action while there is current flowing through the pile.

Still another object of this invention is to provide a carbonv pile regulator in which separable contacts formed of arnateriall capable of withstanding 'a certain amount of arcing are provided between the terminal discs of the carbon pile and the elements exerting pressure on said terminal discs.

A further object of this invention is to provide a lcarbon pile regulator in which separable contacts are provided between the terminal discs of the carbon pileand the elements exerting pressure on said terminal discs and in which the separable `contacts are formed of material capable of withstanding a certain amount of arcing.

A still further object of thislinvention is to provide a carbon 4pile regulator suitablev for use in installations in which vibratory forces exist longitudinally of the axis'of the carbon pile and inwhich means having pairs of separable contacts are provided engaging each end of the carbon pile which contacts are more easily separable than are the adjacent discs of the carbon pile.

Yet another object :of the present invention is to provide a carbon pile regulator provided with means whereby even when subjected to violent vibrations the regulator ywill operate normally until the carbon pile resistance is such as to reduce the current to within a value that can be accommodated by the usual contact forming material beyond which resistance the apparatus operates as a vibratory or Tirrill type regulator.

With these and other objects in view as will appear more fully hereinafter, the present invention comprises the parts and combinations shown in the drawing and set forth in the following description. l

In the drawing the single gure is a more or less diagrammatic sectional View of a carbon pile regulator constructed in accordance with the present invention.

In carbon pile resistances such as employed in regulators of the type set forth in my Patent No. 2,268,718, granted January 6, 1942, the resistance Varies substantially inversely as the pressure applied to the carbon pile.

4If such a carbon pile is subjected to vibrations in line with its axis the minimum pressure (which corresponds to the highest limit of resistance) to obviate separation of the discs 'must be of the order of the mass weight of the pile multiplied by the acceleration involved in the vibratin mass.

If acarbon pile weighs approximately .0235 pound and is subjected to a vibration in line with the axis of the pile approximately equal to a value of 10 G. the minimum Weight on the pile to maintain the discs in Contact with each other and prevent separation thereof should not be less thany .235 pound.

If it be assumed that the resistance of such a carbon pile when the pressure exerted 'thereon is at a minimum would be ohms and it was desired to reduce the value of this resistance to 0.5 ohm, it would be necessary to increase thel minimum pressure exerted on the pile in a ratio of :1, that is in the particular instanceinvolved where the pressure on the pile should be not less than .235k pound, the minimum pressure must be approximately 28 pounds at the beginning of operation of the carbon pile in a controller installation.

In regulators of the type referred to in my above-described patent the pressure on the carbon pile is exerted by a spring and to reduce this pressure the spring force is opposed by an electro'magnetic force.

sired resistance value.

Now if it further be ccnsideredthat the regulator including the carbon pile referred to above must be accurate within i2% the 28 pounds pressure must be substantially only 8% of the The difference of these two forces acts on the carbon pile to give it a decounterbalancing forces present in the magnet and spring system for controlling the pressure on the carbon pile. Under such conditions the equilibrium force required would be 350 pounds. Obviously this is not practical especially in aeronautical installations where the weight and bulk of a regulator capable of producing and sustaining such opposing forces would be too great.

The extreme unusual or emergency conditions set forth above will exist in aeronautical instab lations only on rare occasions and then for very short periods of time, one particular instance of the existence of such conditions taking place in power dives with no load on the generator.

In accordance with the present invention it has been found that a carbon pile may be so assembled in a regulator of the type set forth in my above-mentioned patent that it will be unnecessary to have extremely high equilibrium forces present in the magnet and spring system to prevent separation of the elements of the' pile under the extreme emergency conditions. This is accomplished by providing means for converting the carbon pile regulator, when such extreme unusual operating conditions exist, into a vibratory or so-called Tirrill type of regulator. The conversion from the Tirrilltype regulator back to the carbon pile type of regulator takes place immediately the exteme emergency conditions terminate.

A carbon pile capable of accomplishing the results pointed out hereinbefore and convertible from the carbon pile type of regulator to the Tirrill type regulator and back again is shown in the drawing.

As shown in the drawing, the controller comprises a carbon pile I consisting of a pluralityv of discs mounted in a ceramic tube 2 which in turn is positioned in the boss 3 of the frame l4. A xed terminal 5 is mounted at one end of the carbon pile and is anchored to the frame 4 through suitable insulating material. A movable assemblage 6 is at the other end of the carbon pile and is attached to the armature 1 of an electromagnet as will be hereinafter described.

Frame 4 has a skirt-like portion 8 in which a series of circumferentially spaced bosses 9 are provided and through which bolts I0 extend.

By means of bolts I0 the frame 4 is attached to the flange II of the housing I2 of electromagnet I3, spacers I3a serving to maintain the housing I2 and frame 4 in proper spaced relation.

Secured to one end of housing I2 is a plate I4 in which the core I5 is threadedly mounted. Flange I6 extends inwardly from the other end of the housing I 2 to a point adjacent the free end of the core and cooperates therewith to form pole pieces for attraction of the armature 1.

An annular abutment II is positioned against the ilange I I and mounted thereon is a bimetallic ring I8 of somewhat conical formation the co nicity of which varies with the temperature. Resting on the conical bimetal ring I8 are the ends of a spring or series of springs I9 which wrap upon the ring I8 as an abutment as the spring is stressed.

The spring member I9 is secured to the armature 'I by screws 2U. A terminal 2| and the `assemblage 5 are attached. to but insulated from the armature 'I and spring member.

Suitable insulating platesv are positioned between parts of the armature-spring assembly.

On the upper end of the carbon pile there is positioned a disc 22 of metal or other suitable conductive material on which is provided a contact point 23 of silver, or other suitable material generally employed for electrical contacts. Contact point 23 is located at the center of the carbon pile.

Cooperating with the Contact point 23 is a conF tact point 24 carried by the end of a screw 25 threadedly mounted in the member 5. A lock nut 26 is provided to maintainv the screw 25 fixed.

In contact with the carbon element at the lower end of the pile is a disc 21 of silver or other suitable contact forming conductive material. Engaging this disc is a cup-shaped contact 28 the contact surface of which is annular and substantially concentric with the axis of the carbon pile. This cup-shaped contact member is carried by the assemblage 6 and has openings 29 formed therein to avoid pneumatic adherence between the same and the disc 21.

The peripheral portion of the cup-shaped contact member 28 is arranged concentrically with the axis of the carbon pile and the contact point 23 is arranged substantially coaxially with the carbon pile axis. With such construction the zone of pressure exerted on the carbon pile will be substantially conical and will avoid any tendency to cause buckling of the pile.

If a carbon pile constructed as above described is utilized as a controller in the electrical system of an airplane. for instance, and the plane, for example, is in a power dive the generator will be driven at its highest speed and in al1 probability the carbon pile will be extended as far as possible in order to increase its resistance. Under these conditions the carbon pile may be subjected to excessive vibration and if the direction of the vibration is longitudinally of the carbon pile there would ordinarily be a considerable tendency for the carbon elements of the pile to Separate from each other with .the consequent disadvantages pointed out hereinbefore. However, with the construction of the present invention as described instead of the elements of the carbon pile separating from each other the separation will take place between the contact points 23 and 24 on .one hand and between the disc 2'! and cupshaped contact member 28 on the other hand. There will be a certain amount of pneumatic adherence between the discs or elements of the carbon pile which will not be so in the case of the contact elements. Consequently instead of elements of the carbon pile separating, the carbon pile will remain intact and any separation will occur at the contacts provided for this purpose.

Now it so happens that when the carbon pile is extended to provide a high resistance the current flowing through the pile will be relatively low and in all probability much below 11/2 amperes which can be handled fairly easily by the contact points 23 and 24 and the contact occurring between-the' disc 2l and the cup-shaped member 28 especially if they are constructed of the conventional materials commonly used for this purpose, i. e., silver, platinum, tungsten and various alloys.

Obviously when the circuit through the carbon pile is broken by reason of the separation of the contact elements provided for this purpose the flow of current will be temporarily disrupted. However, since the frequency of the vibrations will probably be high, the break will be instantaneous and the circuit will be shortly re-established. Actually under the conditions described, the device will act as a vibratory or Tirrill l type regulator-.during the .conditions of excessive vibration. v

Since the equipment will be operated under conditions producing extreme vibrations .for such a comparatively short period of time and for such infrequent intervals, the normal operation of the carbon pile will be very little disrupted. Furthermore, since the voperation of the device .as a vibratory or Tirrill type regulator will .prevent any damage to the electrical system during the extreme emergency ccnc'l-itions'the electricalsystem of the equipment will be fully protected at `all times.

The present invention contemplates the provision of means to lprotect the separable contacts according to any of the usual methods such as shunting a resistance,v capacitance, a rectifier or combination of these across the separable contacts. justment the changeover from carbon pile control to carbon pile plus vibratory contact control can take place without appreciable change in the voltage of the circuit controlled.

Having described my invention, I claim:

1'. An electric regulator comprising a carbon pile included in a circuit to be regulated, means for exerting a pressure on said pile to vary the resistance thereof, and means having separable contacts also included in said circuit and interposed 'between the ends of the carbon pile and the means for exerting a pressure on the pile, the separable contacts being more easily separable than the elements of the carbon pile and being mounted to vibrate like the vibratory contacts of a Tirrill type regulator in response to external vibrations acting axially of the carbon pile.

2. An electric regulator comprising a carbon pile included in a circuit to be regulated, means for exerting and varying a pressure on said pile in response to characteristics of an electric current in said circuit, and means responsive to vibrations longitudinally of the pile and just short of an intensity suicient to separate the elements of the carbon pile under the pressure exerted thereon for vibrationally breaking and remaking the circuit through the carbon pile while the vibrations continue.

3. An electric regulator comprising a carbon pile included in a circuit to be regulated, means for exerting a pressure on said pile to vary the resistance thereof, and means having separable contacts also included in said circuit and associated with elements of the carbon pile, the separable contacts being more easily separable than the elements of the carbon pile and being mounted to vibrate like the vibratory contacts of a Tirrill type regulator in response to external vibrations acting axially of the carbon pile.

4. An electric regulator comprising a carbon pile included in a circuit to be regulated, xed means engaging one end of said pile, means responsive to a variable pressure for engaging the other end of said pile, and means having separable contacts also included in said circuit and interposed between the xed means and the end of the pile which it engages and between the means for exerting a pressure on the pile and its associated end of the pile, the separable contacts being more easily separable than the elements of the carbon pile and being mounted to vibrate like the vibratory contacts of a. Tirrill type regulator in response to external vibrations acting axially of the carbon pue 5. An electric regulator comprising a carbon It is found that with proper normal adpile included .in a circuit to be regulated, fixed means engagingone end of vsaid pile, means responsive to the .differential action of a spring and an electromagnet for exerting pressure on the `other end of the pile, and means having separable contacts also included in said circuit and interposed between the ends of the lcarbon pile and the means in engagement therewith and being mounted to vibrate like the vibratorycontacts of a Tirrill type regulator in response to external vibrations acting axially of-the carbon pile.

6. A n electric regulator comprising a carbon pile included in a circuit t0 be regulated and any abutment vadjacent one end of said pile, means having separable contacts also included in 4said circuit and interposed between the abutment and the adjacent end of the pile, a differential spring and magnet system exerting pressure on said pile and positioned adjacent the other end of the pile, and means having separable contacts interposed between said other end of the pile and the differential spring and magnet system, the separable contacts being more easily separable than the elements of the carbon pile and being mounted to vibrate like the vibratory conta-cts of a Tirrill type regulator in response to external vibrations acting axially of the carbon pile. 7. An electric regulator comprising a carbon pile included in a circuit to be regulated and an abutment positioned adjacent one end of the pile, means having separable contacts also included in said circuit and interposed between the abutment and said end of the pile, said separable contacts being positioned axially of the pile, means for exerting the pressure on the other end of the pile, and means having separable contacts also included in said circuit and interposed between the pressure exerting means and. the corresponding end of the pile, said last-mentioned separable contacts being of annular formation and posi tioned concentrically of the axis of said pile, both said separable contacts being arranged to vibrate like the vibratory contacts of a Tirrill type regulator in response to external vibrations acting axially ofthe carbon pile, p

8. An automatic electric regulator comprising a carbon pile, arc-resisting cooperating contacts one of them electrically connected with one end of the pile, and an electromagnet and spring acting in opposition to exert variable pressure upon said contacts and solely through them on the pile.

9. An automatic electric regulator comprising a carbon pile, terminals for connecting said pile to an external circuit, arc-resisting cooperating contacts included in series between said pile and said terminals, and an electromagnet and spring acting in opposition t-o exert variable resistancedetermining pressure upon said contacts and through them on the pile.

l0. An automatic electric regulator comprising an electromagnet, an abutment and a xed contact secured to said electromagnet, an armature adjacent te said electromagnet, a spring resting and wrapping on said abutment and secured to said armature opposing the pull of the electromagnet upon it, a moving contact carried by said armature, and a carbon pile having contactmaking end plates located between said fixed and moving contacts and receiving through them the resistance-determining pressure of said spring. 11. An automatic electric regulator comprising an electromagnet, an abutment and a fixed contact secured to said electromagnet, an armature adjacent to said electromagnet, a spring resting and wrapping on said abutment and secured to said armature opposing the pull of the electromagnet upon it, a moving contact carried by said armature, a carbon pile having contact-making end plates 1ocated between said fixed and moving contacts and receiving through them the resistance-determining pressure of said spring, and terminals for connecting the regulator to a circuit to be regulated, said terminals being electrically in series with said fixed and moving contacts and the carbon pile.

12. A regulator as in claim 11 in which the fixed and moving contacts are of small area.

13. An electrical regulator comprising a carbon pile, terminals by which the regulator is con- 15 nectible to a circuit to be regulated, said carbon pile being in series with said terminals, xed means engaging one end of the carbon pile, means responsive to the differential action of a spring and an electromagnet for exerting pressure on the other end of the pile, and means having separalole contacts interposed between the ends of the carbon pile and the mea-ns in engagement therewith, said separable contacts being in series with 10 the pile and between it and said terminals and being mounted to vibrate like the vibratory contacts of a Tirrill type regulator in response to external vibrations acting axially of the carbon pile.

FREDERICK NEWTON. 

